A fixing device that is used for an image forming apparatus of an electrophotographic type has a fixing roller conveying a recording sheet such as a pressing roller and a heating roller. For example, JP-B-3,382,611 discloses, as a fixing roller, a pressing roller or a heating roller having a core bar, an elastic layer that is provided around the core bar and a fluorine resin tube that covers the elastic layer.
In the fixing roller of the related art, when the fixing roller is not heated, creases are generated on an entire surface thereof. Meanwhile, when the fixing roller is heated, the surface thereof becomes smooth. When the recording sheet is conveyed by the fixing roller that is smooth and has an axially straight shape, wrinkles extending in a conveyance direction are generated on the recording sheet.